Motor and Sensory assessment: Motor block of femoral nerve, and sensory block of the femoral, saphenous, and lateral femoral cutaneous nerves will be evaluated by a blinded observer every 5 minutes for a period of 30 minutes post block insertion. A 22 G hypodermic needle will used to assess sensation in the femoral nerve distribution: middle third medial thigh, lateral femoral cutaneous nerve: lateral thigh, and saphenous nerve: anteriomedial middle third leg . Sensation will be graded as 0 = normal sensation, 1 = dull sensation, and 2 = no sensation. Motor block evaluation was graded as 0 = full power, 1= partial block (paresis), 2 = complete block (paralysis). The quadriceps muscle strength will be assessed by grading the ability or inability to extend the leg of the operated limb against gravity after the hip is passively flexed at 45°. Complete femoral nerve block will be defined as complete loss of a sharp sensation at middle third medial thigh with complete inability to extend the knee joint after hip flexion at 45º after 30 minutes post block insertion.